The feeling of harmony and anticipation is almost palpable at Stamford Bridge right now. It has engulfed Chelsea since early June, restoring a love affair many thought was over for good, and it's been brought on by the return of one man—Jose Mourinho.

Back at Chelsea as manager after six years away following his departure in 2007, the Portuguese manager is expected by many to pick up where he left off after his first spell in charge in West London.

Under Mourinho's tenure, Chelsea won back-to-back Premier League titles, two League Cups and made history by becoming the first team to lift the FA Cup at the redeveloped Wembley. In short, they became the most successful team in England.

On the surface, this time out he faces an altogether different challenge to the one that greeted him in 2004-05. The Premier League is much-changed and Chelsea are no longer the only club with the financial clout of a sugar daddy owner as they compete with four other teams for the title. The Blues have joined Europe's elite by winning the Champions League and success is no longer an expectation, but a demand.

Yet for all the change, he finds a club in a similar position to the one he joined from Porto; a club facing many of the same problems it did a decade ago as it sought to establish itself.

It's taken Roman Abramovich longer than he perhaps would have liked, but Chelsea have gradually replaced their old guard with some of Europe's rising stars. And similar to when Mourinho first arrived at Stamford Bridge, they're a little wet behind the ears and in need of the Midas touch brought by a man with power to help them scale the heights expected.

In 2004 it was Frank Lampard, John Terry and Didier Drogba. Now, the Class of 2013 is Eden Hazard, Juan Mata and Romelu Lukaku.

Qualifying for the Champions League and lifting the Europa League last term may have papered over the cracks for Chelsea, but their ability to concede victories from winning positions was difficult to disguise.

For all their style and verve under Roberto Di Matteo and subsequently Rafa Benitez, there was no hiding the fragility that ultimately cost them the title.

Benitez made a positive impact in many areas during his brief reign and deserves credit for transforming their season from one destined for failure into a success, but the Spaniard couldn't address all their shortcomings.

In his 26 league matches in charge, Chelsea picked up 51 points (a total of 75 in all) to finish third behind Manchester City and champions Manchester United. During that time they dropped 14 points from winning positions, a stat that could have cost them Champions League qualification and certainly rendered their title aspirations over long before May.

Indeed, with a goal swing of +9 in their favor, Chelsea would have finished with a goal difference two better than United's +43, thus making them champions.

It's all hypothetical, sure, but it doesn't hide the fact Chelsea's season ended with questions of "what if?" hanging over it, despite their success in the Europa League.

Under Mourinho, history tells us this isn't going to happen. In his first year in charge, Chelsea lost one game and conceded just two points from winning positions all season, drawing 2-2 with Bolton Wanderers at Stamford Bridge in November.

The following season—when Chelsea won the Premier League for a second time, coming with a record haul of 95 points—they dropped a mere four from winning positions.

There were no "ifs", no "buts" and certainly no "maybes." Chelsea were England's finest, and they did it with the ruthless streak that defines a Mourinho team.

Mourinho's Chelsea were a juggernaut; they were hard to beat and the moment they scored, the desire and confidence was visibly sucked from their opponents.

Chelsea (circa 2004-06) were a ruthless force to be reckoned with and as Mourinho's players returned for pre-season training earlier this week, you can be sure their fitness wasn't the only thing on his list of improvements in the coming weeks.

Talk of a "winning mentality" at clubs has become cheap in recent years. It's become a term bandied around by those lacking the imagination or vocabulary to properly describe the impact of a coach or manager.

This writer is probably both, but as the new season approaches, expect that "winning mentality" to be the first thing Mourinho will be putting right at Chelsea this summer.